Abstract Stroke is the most common cause of chronic disability for adults in the United States, with 65% of individuals after stroke unable to incorporate the hemiparetic upper extremity into daily function. Even mild impairment of upper extremity function after stroke results in significant limitations in daily function and has been demonstrated to negatively impact health-related quality of life. The major objective of this study is to identify the biomechanical variables that predict amount of use of the arm at home. The kinematics and kinetics of the upper extremity during reaching and grasping tasks will be measured in the laboratory and the amount of use of the arm in the home environment will be assessed with portable accelerometry, Motor Activity Log and experience sampling methods. We will identify the characteristics of arm and hand motor performance that best predict significant arm use at home. PUBLIC HEALTH RELEVANCE: Project Narrrative Stroke is the most common cause of chronic disability for adults in the United States, and are a prevalent condition in Veterans. The proposed project intends to compare laboratory-based clinical/biomechanical measures of hemiparetic arm performance with actual arm use in the "real - world" setting. Understanding the complex relationship between laboratory motor performance and the amount of arm use at home will provide guidance on how to most efficiently target therapeutic interventions. The proposed work has the potential to decrease the health care burden placed on the VA and other Federal agencies by stroke patients and to improve their functional independence and quality of life.